Disgrifiad o´r Safle 1. Bryn Celli Ddu is a Late Neolithic passage grave in the European Atlantic tradition, excavated and partly restored in the mid to late 1920s by W J Hemp (Hemp 1930). It comprises an outer circular stone kerb c. 26m diameter, with an inner stone arc, both of which encircle a simple passage tomb whose entrance lies on the east side. Hemps' original hypothesis, that the tomb was built within a ruined henge, is nowadays seen as problematic.

The passage tomb is one of the finest of its kind in Wales. The c.7m long inturned forecourt and stone-lined entrance passage gives access to a central polygonal chamber made of large slabs. In the north angle of the chamber is a 1.7m high smoothed stone pillar, interpreted as a 'protectress' or tomb guardian in the style of Breton tombs, or a phallic symbol. One of the chamber stones bears a small spiral carving which is probably Neolithic. A solar alignment on midsummer sunrise, first postulated by Sir Norman Lockyer in 1909, was finally proven and documented by Dr Steve Burrow of the National Museum Wales in 2005. A central pit contained the most richly decorated Neolithic carved stone in Wales. The original is in the National Museum Wales, with a cast on site.

Bryn Celli Ddu sits at the heart of a ritual landscape, with a plough-levelled cairn just to the south (NPRN 309540), a standing stone to the south-west (NPRN 302503) and a cup-marked rock to the west (NPRN 415847). The arrangement of the passage tomb and style of the carvings has similarities with the passage tomb of Barclodiad y Gawres on western Anglesey (NPRN 95545).

2. Excavations were carried out alongside the monument on a Bronze Age cairn by Dr Seren Griffiths from the University of Central Lancashire, for Cadw, 2017-2019. 'UCLan students and staff led by Dr Seren Griffiths have been working on understanding the multi-phase landscape around the Bryn Celli Ddu passage tomb. The passage tomb has a solar alignment, so that during the summer solstice the sun rises and shoots down the passage tomb to illuminate the chamber. Photogrammetry, laser scanning and excavation by the team have identified important early features and discovered new rock art panels. Bryn Celli is an internationally renowned monument with several phases of development, including rare Mesolithic evidence, and possibly a very early henge monument. The team have also recently laser scanned the nearby passage tomb at Barclodiad y Gawres to record and analyse the rock art, contributing to the re-interpretation of the monument' (Text from: https://www.uclan.ac.uk/about_us/case_studies/bryn-celli-ddu-passage-tomb.php).